Technical 1.3 uno turbo owners- coolant temp help

[beau]

my uno turbo had a small leak from the thermostat housing.

it used to run at exactly half way on the temp guage, and rise to 'just' over half way in traffic then quickly dropping to just under half way/half way depending on town or a run.

having just fitted a new thermostat housing my temp guage is now sitting at the bar past half way, and just past that in town, rising to 2 bars past half way on the guage in traffic, where it will then spill its coolant out every where.

my top radiator hose gets very hot to touch (cant hold it ) mean while my lower radiator hose is just hot (can hold it)- now surely this means my new thermostat is only slightly opening or staying closed does it not?

 

[beau]

i have today measured coolant temps around the engine after being run for 20 minutes.

using a infra-red lazer digital temp thing-

coolant bottle- 72 degrees
top rad hose- 80 degrees
lower rad hose- 77 degrees
bottom of radiator- 85 degrees
top of radiator- 92 degrees
rear metal coolant pipe behind water pump- 97 degrees

the fan was cutting in/out every few minutes as normal at this temp.

the temp guage was showing-

now to me this shows a faulty over reading temp guage does it not?

what do the cooling sensors do, i can see one in the rad and one in thermostat housing, any others? what one controls the fan and what one the guage?

 

[Louie Bee]

ain't there 3 coolent temp sensors like on the fire engine?..

One in the rad with 3 wires for which is the fan switch (obviously senses the rad temp and controls the 2 speed fan) your slow fan speed resistor has probs fallen to bits like mine, so the slow speed won't cut in and the temp will keep rising till the fast speed temp is activated . I bypassed this resistor so I just get a fast fan at the lower temp . The resistor is hidden away below the fan but you can follow the wire off the temp switch.

I'd guess the temp sensor on the thermostat is for the ECU so it knows how to fuel.

If So, and It's like the fire engine, the temp sensor on the head (I'm guessing the one above plug 2 on the turbo) would be for the gauge on the dash , I'm not sure if it's oil or water and as I've sold my spare head I'm not removing it to check.

try pulling the wire out to see what happens on your dash (Obv. with the engine off

 

[beau]

ain't there 3 coolent temp sensors like on the fire engine?..

One in the rad with 3 wires for which is the fan switch (obviously senses the rad temp and controls the 2 speed fan) your slow fan speed resistor has probs fallen to bits like mine, so the slow speed won't cut in and the temp will keep rising till the fast speed temp is activated . I bypassed this resistor so I just get a fast fan at the lower temp . The resistor is hidden away below the fan but you can follow the wire off the temp switch.

I'd guess the temp sensor on the thermostat is for the ECU so it knows how to fuel.

If So, and It's like the fire engine, the temp sensor on the head (I'm guessing the one above plug 2 on the turbo) would be for the gauge on the dash , I'm not sure if it's oil or water and as I've sold my spare head I'm not removing it to check.

try pulling the wire out to see what happens on your dash (Obv. with the engine off

i was thinking the one on the thermostat would be for the guage tbh, just because this is the only sensor i touched, temp guage seemed 'ok' i replaced the thermostat, i cleaned the gunk from the sensor in the stat housing, and since then temp shown on the guage has been high.

il try unplugging sensors and see if any stops the temp guage soon, but the engine cuts out when u unplug the sensor on the stat, which i doubt it would if it was just temp guage one

and you'll have to give me a talk to on how to make the fan run high speed i have no idea what you mean tbh

 

[beau]

right i know what they do now for sure.

stat one is indeed for ecu control.
rad is indeed for the fan control.
one in front of head is for temp guage.

so next thing is working out why is the temp guage reading about 110 degrees when the coolant bottle is 70 degrees and the rad is about 90 is that about right? is it over heating or not?

 

[Louie Bee]

Well did yon fill up with as much water (Or more than) you let out?I got an air lock when I filled my Uno as I knew it should have taken way more water than it did.. as there is no bleed I had to get the old smackers round the header tank… and blow

Not sure how or why as I’d had all the hoses and rad off and cleaned, matrix too but there you go.

Mark showed me how to check if the water pump is good.. with a COLD engine, start the engine and remove the rad cap.. can you se a jet of water firing into the top of the header tank from the turbo return pipe? It should get faster as you rev the engine.

Or is it a trickle at idol? Or even non existent?

As for the fan switch? Look to see if the temp switch on the rad has 3 wires coming off it. Follow the white wire to the coil resistor thingy and short the wires that connect to this coil together. Note that the coil may have rusted away completely like mine had.

I used a fuse just holder cos it has male lucar spade connectors so no cutting of wires for if I ever find a working resistor.

 

[beau]

Well did yon fill up with as much water (Or more than) you let out?I got an air lock when I filled my Uno as I knew it should have taken way more water than it did.. as there is no bleed I had to get the old smackers round the header tank… and blow

Not sure how or why as I’d had all the hoses and rad off and cleaned, matrix too but there you go.

Mark showed me how to check if the water pump is good.. with a COLD engine, start the engine and remove the rad cap.. can you se a jet of water firing into the top of the header tank from the turbo return pipe? It should get faster as you rev the engine.

Or is it a trickle at idol? Or even non existent?

As for the fan switch? Look to see if the temp switch on the rad has 3 wires coming off it. Follow the white wire to the coil resistor thingy and short the wires that connect to this coil together. Note that the coil may have rusted away completely like mine had.

I used a fuse just holder cos it has male lucar spade connectors so no cutting of wires for if I ever find a working resistor.

i dont think its air locked, it took about the same amount of water but cant be 100% sure, but it seems odd to me that i replaced the stat and its now over heating- surely it can only be a dodgy stat or a air lock, just finding out which, might re-fit the old stat and see what happens, but its alot of hastle...

 

[rawill]

I am not sure about what is going on but, you checked the temp with the infra red gun. Do you trust it. If you do I would check the temp sensor or try a new one. You could have had 2 faults, a sensor and a thermostat. It has been known, ask me how I know!

It would have been interesting to know what the infra red gun said with the old thermostat.
Can you get different temp opening thermostats. Did you get one that is too high?

 

[SteveNZ]

i have today measured coolant temps around the engine after being run for 20 minutes.

using a infra-red lazer digital temp thing-

coolant bottle- 72 degrees
top rad hose- 80 degrees
lower rad hose- 77 degrees
bottom of radiator- 85 degrees
top of radiator- 92 degrees
rear metal coolant pipe behind water pump- 97 degrees

the fan was cutting in/out every few minutes as normal at this temp.

the temp guage was showing-

now to me this shows a faulty over reading temp guage does it not?

what do the cooling sensors do, i can see one in the rad and one in thermostat housing, any others? what one controls the fan and what one the guage?

Faulty thermostat or air locked - the rear pipe is for cool coolant from the radiator, 97 is way too hot, (is rad pressurized?) its hotter than the top of the radiator which should be the hottest.

Is the self bleed hose ok? also is the coolant from the turbo flowing well (into the top of the bottle)?

 

[alexGS]

Yeah I agree with Steve - the small pipe that attaches to the top-left end of the radiator and goes back to the expansion tank - pull that pipe off the radiator and make sure you get a good stream of green. If not, probe it with a wire. I've found that silts up repeatedly on mine - it's essential to be clear, so that the system self-bleeds.

The Uno Turbo cooling system is actually a very good design, in my opinion - better than on the other Unos where the radiator has a bleed screw to open and the heater hoses are at a slightly higher point than the filler, making it easy to get an air lock there (which is why some models have a bleed screw on the heater hoses). On the Uno Turbo, the filler is the highest point, so there should be no air lock problems at all provided all the pipes are clear.

After switch-off it's normal for coolant to 'burp' into the expansion tank from the turbo, if the turbo is hot (it's often well past boiling point down there). I guess that is why the system has to be self-bleeding, otherwise it would be giving itself constant airlocks as parts of the system boiled! Mine usually isn't that hot when I switch off, as I drive with no boost for the last few kilometres home

I fitted a new thermostat to mine, many years ago, and the temperature runs at the thin line before half-way (80 degrees), unless the engine is being caned mercilessly at 1 bar boost around a track on a hot day, in which case it goes as high as you show and the oil temperature will be the same. In England at this time of year, no way should it be that high... I believe the Uno Turbo has a slightly cooler thermostat than the other Uno models (was it a Turbo one you fitted or one for another model?), but right now, I think you should trust the gauge and solve the airlock problem.

One more thing - switch the ignition on and without the engine running, stand on the brake pedal a few times. If the gauges fluctuate, that means a fault with the rear light cluster earth. Seriously! I have had that affect my fuel gauge before, and it could affect the temperature gauge too.

-Alex

 

[beau]

i have fitted my old thermostat back in now, and its back to normal, sits between mark below half way and half way, driven it for a while and it doesnt go past half unless u leave it for 10 mins idling, but all in all- seems fine.

so dodgy stat you reckon? doubt it was air locked cos i flushed the coolant out a few times with the new stat in and it didnt work each time, filled it up once with old stat and been fine.

 

[beau]

does anyone know what the thermostat is rated at?

my new one is 85 degrees, that seems too high to me, so anyone know?

 

[rawill]

My Unos have the Tstat in the housing. so I never check the temp on it. But I have just put an 82 in my Saab and it is running too cool, (it was the only one the shop had and I needed it in a hurry) I will be putting an 89 in soon and it will run where it is supposed to.

Haynes 2.1
1116/1301 engine TStat opens at 83-87 fully open at 95.

998/1108 85-90 fully open 100
1301 Turbo ie 78-82 fully open 95
1372 80-84 fully open 95


Hope that helps, Haynes is great and you can download it.

 

[beau]

well not sure what to do other than 'drill out' the thermostat on the new housing.

old stat works fine, new one just doesnt seem to open.

 

[rawill]

well not sure what to do other than 'drill out' the thermostat on the new housing.

old stat works fine, new one just doesnt seem to open.

If you want to be sure the new one is dodgy I would try it again, just to be sure it is not working properly. If it does not work take it back and get another new one. Assuming it is a new one you are trying.

Otherwise can you heat it up in a pot with thermometer. I have done that to check opening and closing.

 

[beau]

If you want to be sure the new one is dodgy I would try it again, just to be sure it is not working properly. If it does not work take it back and get another new one. Assuming it is a new one you are trying.

Otherwise can you heat it up in a pot with thermometer. I have done that to check opening and closing.

it is a brand new one, i gave it back to them today saying it dont work so cant try it again lol, it needs a new water pump so im going to fix this first and go from there i think.

 

[rawill]

it is a brand new one, i gave it back to them today saying it dont work so cant try it again lol, it needs a new water pump so im going to fix this first and go from there i think.

Sounds like a plan

 

[SteveNZ]

Did you try heating it up in a pot to 95 degrees? did it open?

 

[beau]

Did you try heating it up in a pot to 95 degrees? did it open?

i havent done.

but the pipe before the stat only reaches about 80 degrees max when the guage reads 3/4 up.

 

[SteveNZ]

Do that next time, its a full proof test. The temp of the pipe is irrelevant or just an assumption at best.